Refillable blade fuse



April 1937- D. E; CARNEY 2,077,823

REFILLABLE BLADE FUSE Filed Sept. 21, 1932 3 Sheets-Sheet 2 j 58 q 68- 7g 4 J2 6.5

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Gite wan April 3 v D. E. CARNEY 2,077,823

REFIILLABLE BLADE FUSE Filed Sept. 21, 1932 3 Sheets-Sheet 3 ,7 73. avwc/vvwn' Carney,

Patented Apr. 20, 1937 one-third to James Magee, one-third to Harry ll. Neaman, and one-third to Marion Herrick Carney, all e 1? Pittsburgh, Pa.

Application September 2i, 1e32, Serial No. (Bil-$ M 8 @laims.

v This invention relates to electric fuses of the enclosed refillable type, and has particular reference to that class of cartridge fuses known in the art as the cartridge blade fuse.

All such fuses have certain characteristics in common in that they include an insulating casing containing a fuse strip assembly made up of a fusible means connecting spaced blade terminals which project beyond opposite ends of the casing. At the casing ends means are provided for holding the fuse. strip assembly in fixed position relative to the casing, and for closing the casing ends, generally slotted washers, sectional discs, and like elements, which are separately assembled and retained in place by the clamping actionof subsequently applied end caps.

It is a requirement of such fuses that the terminal blades be restrained against rotation with respect to the fuse. casing and at the same time that they be restrained against axial movement longitudinally of the casing in either direction.

An object of the present invention is the provision of a fuse casing end cap having selfcontained means for holding the terminal blade of a fuse, with which the cap is associated,

against rotation with respect to the fuse casing and alsofor locking the fuse terminal against axial movement longitudinally of the casing.

Another object is the provision in a fuse of an end cap for a fuse casing, combining in a unitary structure, means for closing the end of a fuse casing, means for locking a fuse terminal blade against rotary or longitudinal movement with respect to the casing, and means for attaching 5 the unit to a casing end.

This application is a continuation as to all common subject matter of my prior applications, Serial Number 470,167, on a Refillable blade fuse, filed July 23, 1930, and Serial Number 365,929, for

Fuses, filed May 25, 1929. 7

Other objects, in addition to such as will be apparent to those skilled in the art, include: the provision in a fuse of this character, of a detachable end cap having self-contained means automatically operable by manipulation of the cap for releasably locking a fuse terminal blade against movement relativto the fuse casing; the provision in such a fuse, of means rotatably associated with a portion of the assembled fuse casing structure, and ,arranged for cooperative locking engagement with a portion of the fuse strip assembly, to restrain the fuse strip assembly against movement axially of the assembled casing; the provision in such a fuse, of an end cap applicable longitudinally of the fuse casing (@l. millim) and having self-contained terminal blade interlocking means for preventing relative movement between the blade and cap axially of the cap; and the provision of an end cap for fuse casings, having casing closure and terminal holding means forming a permanent part thereof.

This specification and accompanying drawings are illustrative of certain physical embodiments of the principles underlying the invention, and constitute the best means I have thus far devised for reducing the invention to practice.

Figure 1 is a perspective of a fuse constructed in accordance with the principles of this invention.

Figure 2 is substantially a longitudinal section through the fuse at a right angle to Figure 1.

Figure 3 is substantially a longitudinal section through the fuse at a right angle to Figure 2.

Figure 4 is an end elevation of the fuse with the cap disposed in unlocked position and having the cover washer of the cap removed.

Figure 5 is a view similar to Figure 4 and illustrating the cap in locked position.

Figure 6 is a section on the line 6-6 ofFigure 4.

Figure 7 is a group perspective of the elements making up the blade locking end cap.

Figure 8 is a section on the line 8-8 of Figure 2.

Figure 9 is a section on the line 9-9 of Figure 2.

Figure 10 is a perspective of the top terminal blade employed in the fuse assembly.

Figure 11 is a perspective of the casing forming one part of the two-part fuse.

Figure 12 is a perspective of the fuse strip assembly forming the other part of the two-part fuse.

Figure 13 is an elevation illustrating the employment of the casing as a work support in refilling a blown fuse.

In detail, the disclosed embodiment of fuse comprises a casing consisting of a tubular shell ll of insulating material over each end of which.

is threaded a metal ferrule head I! provided with an outwardly. extending reduced externally threaded portion l3 having an internal diameter identical with that of the shell. The heads l2 are permanently fixed to the shell by suitable retaining elements l4.

As shown in Figure 8, each external end of the heads I2 is formed with diametrically opposed integral webs l5 having opposed edge opening notches I6. The heads are so fixed to the shell that the webs l5 and notches l6 will be in fixed longitudinal alignment at each end of the casing.

The casing is designed to receive a fuse strip assembly comprising two terminal blades l1 and less than that of the casing.

l8 adapted to project beyond the casing ends and having reduced portions I9 and 28 connected by fusible link means here shown as a plurality of bowed fuse links 2| having suflicient inherent stiflness to maintain the terminal blades in properly spaced and aligned relation in handling, thus eliminating the need of an insulating bridge. The shank l9 of blade carries a substantially rectangular flash bar 22 centrally slotted to embrace the shank and abutting the inner edge of the larger contact portion, being rigidly secured to the shank by solder and by striking over the metal thereof. This bar is narrow, having a width not much greater than the thickness of its associated blade and at each end .the bar extends slightly beyond the edges of the blade, being curved in conformity to the casing head wall.

As best shown in Figure 10, the terminal blade II has its edges recessed to provide shoulders 23 in advance of the flash bar. These shoulders each form the rear wall of the formative recess, the forward wall 24 of each recess being inclined outwardly from the recess bottom to the edge of the blade.

The blade I8 is formed with a permanently secured closure cap 33 for the casing end, consisting of a circular plate 28 embracing the blade and carrying on its inner face a guide plate 29 shaped to seat in and conform to an end of the casing with inturned guide fingers 38 seating in the casing head notches l6. Plates 28 and 29 are rigidly connected as a unit by screws or rivets 3| and the unit thus formed is fastened on the blade between the flash bar and a cotter pin 32.

Forming a part of the cap 33 and rotatably associated with the closure plate 28 is a rotatable sleeve portion 33 threaded for engagement over the casing head l3 and formed with an integral annular flange 34 internally thereof intermediate the sleeve ends. A covering washer 35 slotted to receive the terminal blade, seats over the outer face of the flange 34 within the confines of the cap and this washer is coupled to the closure plate 28 by rivets or screw bolts 36, the shanks of which, between the washer and plate, are surrounded by spacer sleeves 31 which maintain a freely rotatable relationship between the washer and plate and the cap flange 34 confined therebetween.

At its opposite end, generally referred to in service as the top, the casing carries an end cap 38 provided with an internally threaded sleeve portion 38 for detachable threaded engagement over the head l3 and having an intermediate, internal, integral annular flange 39 of an internal diameter In cross-section the flange is shaped to engage in and conform to the recesses 23-24 of the terminal blade H, which, in a certain position of the cap, may be moved axially of the casing through substantially U-shaped diametrically opposed recesses 48 in the flange, the depth of the recesses being such that when aligned with the blade the same may be passed freely therethrough.

Rotatably coupled to and forming a permanent part of the end cap 38 is a casing end closure plate 4|, which when the cap is threaded home, seats over the head l3 and closes the end of the casing. Plate 4| is in the form of a flat disc provided with a central slot 42 to receive the terminal blade. Rigzdly attached to the inner face of the closure plate, as by rivets 43, so as to form a unit therewith, is a guide member 44 comprising a plate shaped to conform to and seat in the end of the adjacent casing head l3 between the webs l5. This plate 44 is provided with inwardly directed guide fingers 45 having rounded tips, which pass through and seat in the notches I6 of the webs l5 when the cap is applied. Plate 44 is also slotted to engage over the terminal blade.

The elements of cap 38 are permanently coupled in freely rotatable relation with respect to each other by means of an outer covering washer 46 centrally slotted to receive the terminal blade and which seats loosely against the outer face of the cap flange 39 being connected to the plates 4| and 44 by rivets or screw bolts 41. Spacer sleeves 48 surround the screw bolt shanks between the cover washer and end closure plate to insure against any binding of these elements against the cap flange which is conflned therebetween. Markers 49 are provided on the outer rim of the cap 38 in diametrical alignment with the flange recesses 48.

In assembling the fuse the unitary and cap I 38 comprising the sleeve 38, plate 4| and covering washer 46, is threaded over an end of the easing head I3, such as the left hand end as seen in Figures 1, 2 and 3. The cap is screwed home to its limit and is then given a reverse turn suflicient to align the markers 49 and the blade slot in the cover washer 46. As washer 46 is fixed with respect to the end closure plate 4| by virtue of the screw bolts 41 the washer and plate will remain stationary, being held against rotation by the engagement of plate 44 and guide fingers 45 between the casing head webs l5 and notches l6 through which the guide fingers pass in advance of the threading of the cap. The cap sleeve 38' and its integral locking flange 39 alone rotates. When the markers 49 align with the blade slot the lock flange recesses 48 will be similarly aligned.

The fuse strip assembly comprisng the blade |8 with its permanently connected end cap unit 1' 33, fuse links 2| and terminal blade I! is then inserted through the open end of the casing from right to left, the blade I! passing through the aligned openings of the end cap unit 38 until the flash bar 22 of the blade engages against cap plate 44 at which point 'the recesses in blade II will occupy the plane of the locking flange 39 and the guide fingers 38 of end cap unit 33 will have engaged the recesses I6 in the webs l5 of the adjacent casing head sufliciently in advance .1

of threading engagement of the cap 33 to anchor the terminal blade |8 against rotation in the casing while the cap is screwed home. The advancing movement of cap 33 causes its flange 34 to bear against plate 28 and clamp the same against the casing end.

With the parts thus assembled the end cap 38 is rotaed to disalign the markers 49 from blade I! whereupon the cap flange 39 moves into the blade recesses 23-24 and interlocks with the blade preventing any axial movement of the terminal blade H with respect to the cap and casing. Due to the fact that the slotted plates 4 44, and cover washer 46 embrace the blade it is evident that the blade will be held against rotation as the seating engagement of plate 44 and guide flngers 45 in the adjacent casing head prevents rotary movement of these elements.

When it is desired to unlock the blade H the cap sleeve 38' is rotated to align the markers 49 with the blade, which will align the notches 48 with the blade permitting it to be moved axially through the cap.

Venting of the fuse is accomplished through a circular vent groove 58 provided in the inner face of the flange 39 in cap 38 and opening to the blade notches 40.

In service the fuse is a two-part assembly, one part A as shown in Figure 11 comprising the casing ll carrying the cap 38, and the other part B, shown in Figure 12, comprising the fuse strip assembly which is inserted in the casing as described.

Referring to Figures 1 and 13 and assuming the fuse to have been blown, a refilling can be accomplished without the necessity of removing a plurality of elements and allowing them to lie on a work bench or shelf and thus pick up dirt and grease. In making a refill'the cap 38 is retractively rotated, its movement causing the lock flange 39 to move out of engagement with the blade I! and placing the notches 4H in registry with the closure plate slot 42.

The cap 33 is then unscrewed, and by virtue of its permanent, non-slidable connection with the blade l8, said blade and cap are removed as a unit. Holding the casing in a vertical position,

as seen in Figure 13, the blade i'i is pushed inwardly and allowed to drop through the casing. 2 Blade I8 is then inserted through cap 38, seating in the slot of, its associated structure until cap 33 rests on cap 38 as seen at the upper part of Figure 13.

New fuse links 2| are then connected to the upstanding blade portion 20, after which the terminal I! is connected with the free ends of the fuse links. This completes the assembly of the fuse strip which is then removed from cap 38 and inserted as an entirety through the open end of the casing, in a manner previously described in detailing the assembling of the twopart fuse thus formed. I

In the refilling operation the casing it serves as a work holder or supporting vise, and no part of the entire fuse leaves the hands of the person refilling.

An important feature of the invention lies in the provision of a clearance of from one ten thousandth to one fifteen. thousandth of an 45 inch between the terminal blade I! and the slots in cover washer 46 and plates 4| and 44, and

between the terminal blade l8 and the slots in cover washer and plates 28 and 29. This clearance permits of a very slight .rotational play 0 of the blades relative to the casing and also of a slight axial rocking of the blades, whereby the blades may align themselves on engagement in the usual fuse holder contact clips, not shown. This self-aligning feature of the terminal blades insures full contact and thus avoids overheating.

I claim:

1. In a fuse, a. casing, an end cap having rotatably detachable engagement with one end thereof, a closure member in permanently coupled connection with said cap and shiftable thereon, a terminal blade movable axially through said closure member and cap, and blade locking means carried by said cap and locking said terminal blade against movement axially through said closure member andcap.

2. In a fuse, the combination with a casing and a fuse strip assembly having a terminal projecting through an end of the casing, of an end cap engageable with the casing end, and means permanently connected to said cap for locking said terminal against axial and rotary movement with respect to the casing.

3. An end cap for fuse casings, including a casing attachable portion, and a fuse terminal interlocking engageable member permanently connected thereto within the confines of the cap.

4. An end cap for fuse casings, including a casing engaging portion, an internal annular flange thereon arranged for interlocking engagement with a terminal blade, and means coupled to said flange for engaging a casing end to prevent rotary movement of the terminal blade with respect thereto.

5. An end cap for fuse casings, including a casing attachable portion, a fuse terminal engageable interlocking member forming a part of said cap, and a casing end closure member loosely coupled to said interlocking member.

6. In a fuse, an end cap comprising a casing engageable sleeve portion, an internal flange on said cap adapted for interlocking engagement with a terminal blade, and a member rotatably coupled to said flange and adapted for fixed engagement with a casing when the cap is applied, said member being arranged to embrace a fuse terminal.

7. An end cap for fuse casings, including a casing engaging portion, an internal annular flange thereon arranged for interlocking engagement with a terminal blade, casing end closure means associated with said flange and engageable with a casing end to prevent rotary movement of the terminal blade with respect thereto, and said flange having a vent groove in the inner face thereof.

8. An end cap for fuse casings, comprising a casing engaging portion, an internal annular flange integral with said casing engaging portion and disposed between the opposite ends thereof, said flange being arranged for interlocking engagement with a terminal blade, and means coupled to said flange for engaging a casing end to prevent rotary movement of a terminal blade with respect thereto,

DANIEL E. CARNEY. 

